Hybrid suspension and tension mechanism for mobile robots

ABSTRACT

A hybrid mobile robot includes a base link and a second link. The base link has a drive system and is adapted to function as a traction device and a turret. The second link is attached to the base link at a first joint. The second link has a drive system and is adapted to function as a traction device and to be deployed for manipulation. In another embodiment an invertible robot includes at least one base link and a second link. In another embodiment a mobile robot includes a chassis and a track drive pulley system including a tension and suspension mechanism. In another embodiment a mobile robot includes a wireless communication system.

CROSS REFERENCE TO RELATED PATENT APPLICATION

This patent application is a divisional application to U.S. patentapplication Ser. No. 11/980,782 filed on Oct. 31, 2007 titled HYBRIDMOBILE ROBOT which is incorporated herein by reference in its entirety.

FIELD OF THE INVENTION

This invention relates to mobile robots and in particular mobile robotsthat can be inverted and mobile robots that have an interchangeableconfiguration between locomotion and manipulation.

BACKGROUND OF THE INVENTION

In the aftermath of Sep. 11, 2001, mobile robots have been used for USAR(Urban Search and Rescue) activities such as searching for victims,searching paths through the rubble that would be quicker than toexcavate, structural inspection and detection of hazardous materials.Among the few mobile robots that were used such as the Inuktun'sMicro-Tracs™ and VGTV™ and Foster-Miller's Solem™ and Talon™, thecapability was very limited in terms of locomotion and mobility. Thecapabilities are further limited if one considers any requirements ofmanipulation with an arm mounted on the mobile robot, and because ofthese limitations in many instances the robotic arm was not used at all.Some of the most serious problems with the robots were the robotflipping over or getting blocked by rubbles into a position from whereit could not be righted or moved at all. None of the robots used on therubble pile searches were successfully inverted after flipping over.These are only some of the several outstanding problems among the manychallenges that are still encountered in the field of small MobileRobots for Unmanned Ground Vehicle (UGV) operations for rough terrainapplications.

Increasingly, mobile robotic platforms are being proposed for use inrough terrain and high-risk missions for law enforcement and militaryapplications (e.g., Iraq for IEDs—Improvised Explosive Devices),hazardous site clean-ups, and planetary explorations (e.g., Mars Rover).These missions require mobile robots to perform difficult locomotion anddexterous manipulation tasks. During the execution of such operationsloss of wheel traction, leading to entrapment, and loss of stability,leading to flip-over, may occur. These events often result in totalmission failure.

Various robot designs with actively controlled traction, sometimescalled “articulated tracks”, were found to somewhat improverough-terrain mobility, but with limited capability to reposition themobile robot center of gravity (COG). The repositioning of COG allows acertain degree of control over the robot stability. Efforts arecontinuously made in designing robots that allow a wider control overCOG location providing greater stability over rough terrains. This isachieved by designing robots with displacing mechanisms and activelyarticulated suspensions that allow for wider repositioning of the COG inreal-time. However, the implementations of such solutions most oftenresult in complex and cumbersome designs that significantly reducerobot's operational reliability, and also increase its cost.

There are numerous designs of mobile robots such as PackBot™,Remotec-Andros™ robots, Wheelbarrow MK8™, AZIMUT™, LMA™, Matilda™,MURV-100™, Helios-II™, Variable configuration VCTV™, Ratler™, MR-1™,MR-5™ and MR-7™, NUGV™, and Talon™ by Foster Miller. They are mainlybased on wheel mechanisms, track mechanisms and the combination of both.As well, some legged robots have been suggested for rough terrain use.However, all of these robots have certain limitations. Specifically theyhave difficulty getting out of certain situations such as if they becomeinverted.

A review of several leading existing mobile robot designs has indicatedthat it would be advantageous to provide a mobile robot wherein eachkinematic link has multiple functions. Further it would be advantageousto provide a mobile robot that is invertible. Similarly it would beadvantageous to provide an invertible mobile robot with an armintegrated into the platform. Still further, it would be advantageous toprovide a mobile robot that has a tension and suspension system. One aimis to increase the robot's functionality while significantly reducingits complexity and hence drastically reducing its cost.

SUMMARY OF THE INVENTION

A hybrid mobile robot includes a base link and a second link. The baselink has a drive system and is adapted to function as a traction deviceand a turret. The second link is attached to the base link at a firstjoint. The second link has a drive system and is adapted to function asa traction device and to be deployed for manipulation.

In another aspect of the present invention an invertible mobile robotincludes at least one base link and a second link. Each base link has adrive system and the base links define an upper and a lower plane. Thesecond link is attached to at least one base link. The second link has adrive system. The second link has a stowed position and an upper andlower plane and in the stowed position the second link upper and lowerplane is within the upper and lower plane of the at least one base link.

In a further aspect of the invention a mobile robot includes a chassisand a pair of track drive pulley systems, one on each side of thechassis. Each track drive pulley system has a front and back pulley, atrack, and a plurality of top and bottom spaced apart planetarysupporting pulleys. Each pulley has a tension and suspension mechanism.

In a further aspect of the invention a mobile robot includes a base, asecond link, an end link and a central control system. The base has abase drive system. The second link is attached to the base link at afirst joint and the second link has a second link drive system. The endlink is attached to the second link at a second joint and the end linkhas an end link drive system. The central control system is operablyconnected to the base drive system, operably connected to the secondlink drive system and operably connected via wireless communication tothe end link.

Further features of the invention will be described or will becomeapparent in the course of the following detailed description.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will now be described by way of example only, withreference to the accompanying drawings, in which:

FIG. 1 shows three perspective schematic views of the hybrid mobilerobot of the present invention wherein a) shows the closed or stowedposition; b) shows an open configuration; and c) shows an exploded viewin an open configuration;

FIG. 2 shows four perspective schematic views of the hybrid mobile robotof the present invention showing the hybrid mobile robot configured formobility purposes wherein a) shows a partially open configuration andshowing the location of a camera; b) shows a second link configured toovercome an obstacle; c) shows the second link configured so that thecamera can view another location; and d) shows the second and thirdlinks configured to overcome an obstacle;

FIG. 3 shows three perspective schematic views of the hybrid mobilerobot of the present invention configured for enhanced traction whereina) shows the second link configured to be engaged with the ground; b)shows the second and third links configured to be engaged with theground; and c) shows the second and third links configured to move overirregular terrain;

FIG. 4 shows three perspective schematic views of the hybrid mobilerobot of the present invention configured for manipulation wherein a)shows the second and third links configured for manipulation; b) showsthe second link configured as a platform and the third link formanipulation; and c) shows the second link configured as a platform onirregular terrain and the third link for manipulation;

FIG. 5 is a perspective view of the hybrid mobile robot of the presentinvention showing a flat or open configuration;

FIG. 6 is a perspective view of the hybrid mobile robot of the presentinvention in the stowed or closed position;

FIG. 7 is a top view of the robot of the present invention in the stowedposition;

FIG. 8 is a top view of the hybrid mobile robot of the present inventionin the open configuration;

FIG. 9 is a side view of the hybrid mobile robot of the presentinvention in the open configuration;

FIG. 10 is a perspective view of the base link track of the hybridmobile robot of the present invention and showing the pulleyarrangement;

FIG. 11 is a side view of the base link track of the hybrid mobile robotof the present invention showing the general pulley arrangement and thetrack tension and suspension mechanism;

FIG. 12 is an exploded view of the base link track of the hybrid mobilerobot of the present invention similar to that shown in FIG. 11;

FIG. 13 is an enlarged front view of the spring housing assembly for thebase link track of the hybrid mobile robot of the present invention;

FIG. 14 is an enlarged perspective view of the spring housing shown inFIG. 13;

FIG. 15 is an enlarged perspective view of the drive mechanism for thebase link track of the hybrid mobile robot of the present invention;

FIG. 16 is a left perspective view of the assembly and drive mechanismof the second and third link of the hybrid mobile robot of the presentinvention;

FIG. 17 is an enlarged left perspective view of the drive mechanismshown in FIG. 16;

FIG. 18 is a right perspective external view of the assembly and drivemechanism of the second and third link of the hybrid mobile robot of thepresent invention;

FIG. 19 is an enlarged right perspective view of the first joint of thedrive mechanism shown in FIG. 18;

FIG. 20 is a right perspective internal view of the assembly and drivemechanism of the second and third link of the hybrid mobile robot of thepresent invention;

FIG. 21 is an enlarged right perspective view of the second joint of thedrive mechanism shown in FIGS. 18 and 20;

FIG. 22 is a schematic representation of an embodiment of the wirelesscommunication layout for use with the hybrid mobile robot of the presentinvention;

FIG. 23 is a schematic representation of an embodiment of the hardwarearchitecture for use with the hybrid mobile robot of the presentinvention wherein a) shows the right base link track including a centralwireless module; b) shows the left base link track and c) shows thegripper mechanism;

FIG. 24 is a schematic layout of the sensors and cameras for the hybridmobile robot shown in FIG. 23;

FIG. 25 shows three possible wireless modules used with the hybridmobile robot of the present invention;

FIG. 26 shows four perspective schematic views of an alternateembodiment of the hybrid mobile robot of the present invention having awheel drive system wherein a) shows a partially open configuration b)shows the second link configured as a platform for enhancedmanoeuvrability and the third link for manipulation; c) shows the secondlink configured as a platform for enhanced traction and the third linkfor manipulation and d) shows the closed or stowed configuration;

FIG. 27 shows four perspective schematic views and a top view of analternate embodiment of the hybrid mobile robot of the present inventionhaving a right and left base link position adjacent to each other with asecond link on one side thereof and a third link nested in the secondlink, wherein a), b) and c) show the open configurations, d) shows theclosed or stowed configuration, and (e) shows the top view of the closedor stowed configuration;

FIG. 28 shows four perspective schematic views of a further alternatehybrid mobile robot of the present invention similar to that shown inFIG. 27 except that the third link is adjacent to the second link on theopposed side of the second link, wherein a), b) and c) show the openconfigurations, and d) shows the closed or stowed configuration;

FIG. 29 shows three perspective schematic views of a further alternatehybrid mobile robot of the present invention similar to those shown inFIGS. 27 and 28 but having the second link on one side of the right andleft base links and the third link on the other side of the right andleft base links, wherein (a) shows the closed or stowed position and b)and c) show the open configurations;

FIG. 30 shows three perspective schematic views and a top view ofanother alternate embodiment of the hybrid mobile robot of the presentinvention similar to that shown in FIG. 4, but having the left and rightbase links joined at each end thereof wherein a) b) and c) show openconfigurations and (d) is the top view of the closed configuration;

FIG. 31 is a perspective view of a hybrid robot of the present inventionshowing cameras and other accessories, an end effecter, and passivewheels on the third joint; and

FIG. 32 shows five schematic views of the hybrid mobile robot of thepresent invention showing alternative configurations for manipulationwherein (a), (b) and (d) are similar to the configurations shown inFIGS. 4( a), (b) and (c), respectively; and FIG. 32( c) shows aconfiguration where the second and third links are deployed towards thebase link tracks; and FIG. 32( e) shows a configuration where the thirdlink is deployed for manipulation purpose and the second link remainsnested between the base links.

DETAILED DESCRIPTION OF THE INVENTION

The present invention introduces a new paradigm of mobile robot designfor locomotion and manipulation purposes that was realized based onidentifying and quantifying the existing gap between the traditionalstructures of typical mobile robots and their range of applications.Typically, a mobile robot's structure consist of a mobile platform thatis propelled with the aid of a pair of tracks, wheels or legs, and amanipulator arm attached on top of the mobile platform to provide therequired manipulation capability. However, the presence of an arm limitsthe mobility. On the other hand, there are several designs of mobilerobots with the ability to return itself when flipped-over, but this isnot possible if the robot is equipped with a manipulator arm. This gapis bridged in the approach herein by providing a new paradigm of mobilerobot design that provides locomotion and manipulation capabilitiessimultaneously and interchangeably. The approach is also a new way ofrobot-surroundings interaction as it increases the mobile robot'sfunctionality while reducing its complexity, and hence reducing its costand increasing its reliability.

The new design paradigm is based on hybridization of the mobile platformand the manipulator arm as one entity for robot locomotion as well asmanipulation. The new paradigm is that the platform and the manipulatorare interchangeable in their roles in the sense that both can supportlocomotion and manipulation in several configuration modes. Such a robotcan adapt very well to various ground conditions to achieve greaterperformance as a prospective product for a variety of missions formilitary, police and planetary exploration applications.

Description of the Design Paradigm

FIG. 1 of the drawings depicts the mobile robot 30 of the presentinvention. If the platform is inverted due to flip-over, the symmetricnature of the design (FIG. 1( a)) allows the platform to continue to thedestination from its new position with no need of self-righting. Also itis able to deploy/stow the manipulator arm from either side. Preferablyrounded and pliable side covers 22 are utilized to preventimmobilization when the robot 30 flips over on either side as shown inFIG. 1( a).

The robot 30 includes two base links 12, link 14, link 16 and two wheeltracks 18. Link 14 is connected between the two base links 12 via afirst joint 19 (FIGS. 1( b) and (c)). The two base links 12 have tracks20 attached thereto. Two wheel tracks 18 are inserted between links 14and 16 and connected via a second joint 21 (FIGS. 1( b) and (c)). Thewheel tracks 18 are used to support links 14 and 16 when used as part ofthe platform while touching the ground. The wheel tracks 18 may be usedpassively or actively for added mobility. Both links 14 and 16 arerevolute joints and are able to provide continuous 360 degree rotation.The robot's structure allows it to be scalable and can be customizedaccording to various application needs.

Modes of Operation

The links 12, 14, 16 can be used in three modes:

-   1) All links used for locomotion to provide desired levels of    manoeuvrability and traction;-   2) All links used for manipulation to provide added level of    manipulability. The pair of base links 12 can provide motion    equivalent to a turret joint of the manipulator arm;-   3) Combination of modes 1 and 2. While some links are used for    locomotion, the rest could be used for manipulation at the same    time, thus the hybrid nature of the design paradigm.

All three modes of operation are illustrated in FIGS. 2, 3 and 4. In theproposed design the motors 24 and 88 (best seen in FIG. 8) used to drivethe platform are also used for the manipulator arm as the platformitself is the manipulator arm and vice versa. In other words, theplatform can be used for mobility while at the same time it can be usedas a manipulator arm to perform various tasks.

Manoeuvrability

FIG. 2 shows the use of link 14 to support the platform for enhancedmobility purposes. Link 14 can also be used for climbing purposes.

Link 14 helps to prevent the robot 30 from being immobilized due tohigh-centering, enables the robot 30 to climb taller objects (FIG. 2(b)), and can help propel the robot 30 forward through continuousrotation. Link 14 is also used to support the entire platform whilemoving in a tripod configuration (FIG. 2( c)). This can be achieved bymaintaining a fixed angle (90.degree. for instance) between link 14 andthe base link 12 while the tracks 20 (shown more clearly in FIG. 10) arepropelling the entire platform. Configurations (a) and (c) in FIG. 2show two different possible configurations for camera use. Configuration(d) in FIG. 2 shows a case where link 16 is used to surmount an objectwhile link 14 is used to support the entire platform in a tripodstructure.

The posture of the tripod configuration as shown in FIG. 2( c) can beswitched by placing link 14 behind the base links 12 instead of in frontof them. This can be achieved by rotating link 14 in a clockwisedirection (180.degree. for instance) while passing it between the baselinks 12. This functionality is effective when it is necessary torapidly change the robot's 30 direction of motion in a tripodconfiguration.

Traction

For enhanced traction, link 14, and if necessary link 16 can be loweredto the ground level as shown in FIGS. 3( a) and 3(b). At the same time,as shown in configuration (c), the articulated nature of the mobileplatform allows it to be adaptable to different terrain shapes andground conditions.

Manipulation

FIG. 4 depicts different configurations of the platform for manipulationpurposes. It can be seen that while some links are used as thelocomotion platform others are used simultaneously for manipulation.Configuration (c) is similar to configuration (b) in FIG. 4 in terms ofmanipulation capabilities; however, configuration (b) is optimal forenhanced traction since the contact area between the locomotion platformand the ground is maximized. Configuration (c) is useful for increasedmaneuverability since the contact area between the locomotion platformand the ground is minimized.

Referring to FIG. 32, five configurations for manipulation are shownwherein FIGS. 32( a), (b) and (d) are similar to those shown in FIGS. 4(a), (b) and (c). Two other alternative configurations are shown in FIGS.32( c) and (e). In FIG. 32( c), the second link 14 and third or end link16 are deployed towards the base link tracks in the opposite directionsuch that the robot's structure allows for greater tip-over stability inorder to carry heavier loads at the end-effecter. In this configuration,the COG of link 16 is closer to the COG of links 12 in order to providemuch greater tip-over stability. FIG. 32( e) shows a configuration wherethe third link 16 is deployed for manipulation purpose, while the secondlink 14 remains folded between the base links 12 to allow manipulationwith enhanced (yet less) tip-over stability but in more confined spaceswithout the second link 14 deployed to support the entire platform.

Mechanical Design Paradigm Architecture

The mechanical architecture of the mobile robot shown in FIG. 5 depictsthe embodiment of the conceptual design paradigm. It includes a pair ofbase links 12 (left and right), a second link 14, a third or end link16, and two wheel tracks 18. Link 14 is connected between the left andright base link 12 via the first joint 19. Two wheel tracks 18 areinserted between links 14 and 16 and connected via the second joint 21.The design also includes a built-in dual-operation track tension andsuspension mechanism 50 situated in each of the base link 12 and isdescribed below. This section describes in detail the platform drivesystem, arm joint design and integration of the arm into the platform.It will be appreciated by those skilled in the art that wheel tracks 18are an example of a means of traction and that other traction meanscould be used.

Along with the challenge and effort to realize the concept into afeasible, simple and robust design, most of the components considered inthis design are off-the-shelf. The assembly views show theplatform/chassis design and the different internal driving mechanismsalong with description of the components used and their function.

The closed configuration of the robot (FIGS. 6 and 7—all links stowed)is symmetric in all directions x, y and z. Although the design is fullysymmetric, for the purpose of explanation only, the location of firstjoint 19 will be taken as the reference point, and it will be called thefront of the robot. In the stowed or closed configuration link 16 isnested in link 14 such that no part of link 16 is above or below link14. Similarly in the stowed or closed configuration link 14 is nestedbetween base links 12 wherein no part of link 14 is above or below baselink 12.

Motors

Referring to FIG. 8, excluding the end effector, the design includesfour motors 24 and 88. Two motors 88 are situated at the back of each ofthe base link 12 and the other two motors 24 at the front. The motor 88at the back of each base link 12 provides propulsion to the track 20attached to that specific base link 12. Both motors 88 at the backtogether provide the mobile robot 30 translation and orientation in theplane of the platform. The motor 24 at the front of each base link 12provides propulsion to one additional link. The motor 24 at the front ofthe right base link propels link 14 and the motor 24 at the front of theleft base link 12 propels link 16 (FIGS. 8 and 9). The fact that alllink motors are situated at the base provides an important feature tothe design since the entire structure's COG is maintained close to theground.

Base Link 1—Tracks

Referring to FIGS. 10 and 11, the right and left base links 12 are eachsymmetric in all directions (x, y & z) and preferably identical in termsof the internal driving mechanisms although the mechanisms situated atthe front of each base link 12 drives a different link.

Preferably, the width of each track 20 is 100 mm. This is wide enough toenhance support and traction over the ground. The tracks 20 used in thisdesign may be off-the-shelf components. In the center of each track 20,there is a rib 23 that fits into a guide located at the center of themain pulleys 26 and 94 outer rim, as well as on all six planetarysupporting pulleys 28 (FIG. 10). This feature prevents the track 20 fromsliding off laterally, thus preventing the tracks 20 from coming off themain pulleys 26 and 94 and all six planetary supporting pulleys 28. Rib23 may be solid as shown herein or serrated.

Built-In Dual-Operation Track Tension and Suspension Mechanism

The tension and suspension mechanism 50 of the supporting planetarypulleys 28 is shown in detail in FIGS. 13 and 14. Each of the supportingpulleys 28 is mounted on a supporting bar 96 (FIG. 10) that is suspendedat each end by a compression spring 32 (FIGS. 12-14). The top of eachcompression spring 32 is supported by a spring guide 48 while the bottomof each spring 32 is seated in a spring housing 92. The ends of eachsupporting bar 96 are guided through a groove in the right base linkwall 34 and left base link wall 36 of the base link 12 as shown in FIG.12. Therefore, each set of three planetary supporting pulleys 28 in thetop and bottom of the left and right base link 12 is suspended by a 2×3spring 32 array. It will be appreciated by those skilled in the art thatthe set of three planetary supporting pulleys 28 is by way of exampleonly and that the number of supporting pulleys may be chosen by theuser. The purpose of the supporting pulleys 28 is dual and they providetwo very important functions. While the bottom three supporting pulleys28 in each base link 12 are in contact with the ground, they act as asuspension system as shown in FIG. 11 at 33. At the same time, the upperthree supporting pulleys 28 will provide a predetermined tension in thetrack 20 as shown in FIG. 11 at 35. This dual operation track suspensionand tension system 50 accounts for the symmetric nature of the designand operation of the mobile robot 30. In other words, if the platform isinverted, the three supporting pulleys 28 that were used as suspensionwill act to maintain the tension in the tracks 20, while the other threepulleys 28 that were used to provide tension in the tracks 20 will actas a suspension system. The required tension in the track 20 and thesuspension stroke can be preset to required values by fastening orloosening the compression nuts 39 (FIGS. 13 and 14). Another usage ofthe spring 32 array is to absorb energy resulting from falling orflipping, thus providing some compliance to impact forces.

Driving Mechanisms

Each motor 24 and 88 is connected to a front driving gear mechanism 70and back driving gear mechanism 90, respectively (see FIG. 12). The backdriving gear mechanism 90 in the rear of each base link 12 providespropulsion to the track 20 and the front driving gear mechanism 70 inthe front of the right and left base link 12 provides propulsion tolinks 14 and 16, respectively. A magnification of the front drivingmechanism 70 is shown in FIG. 15.

Each driving mechanism includes a miter gear 40 attached to the motor 24and 88 shaft. The corresponding miter gear 98 is attachedperpendicularly to the left base link wall 36 through a stationary shaft42 and sleeve bearing 44. One sprocket 46 is attached to the miter gear98 while the other sprocket 100 is attached to first joint 19 drivingshaft 62 and supported by the front axle 64 via sleeve bearings 66 asshown in FIGS. 16 and 17. Sprocket 100 is driven by sprocket 46 via ANSIchain 102. Depending on whether the driving gear mechanism 90 and 70propels a pulley 26 and link 14 or 16 respectively, the only part thatis different in each driving mechanism is the driving shaft (drivingshaft 62 for driving link 14 and driving shafts 68 and 82 for drivinglink 16).

As shown in FIG. 12, the back pulley 26 is supported by a stationaryaxle 60 via two radial ball bearings 54 and one thrust bearing 56. Thethrust bearing 56 eliminates any direct contact between the back mainpulley 26 and the front main pulley 94 and the right base link wall 34to ensure smooth and frictionless running of each main pulley 26 and 94and to eliminate any gaps at the same time. Each of the back drivingmechanisms 90 is propelling a driving shaft 58 that is connected to theback pulley 26 in a flange connection and is mounted on the back axle 60in a concentric manner via sleeve bearing.

As shown in FIG. 15, the right front driving mechanism 70 is propellingfirst joint 19 driving shaft 62, which is connected to link 14 in aflange connection and is mounted on the front axle 64 in a concentricmanner via sleeve bearing 66.

As shown in FIGS. 18 to 21, the left front driving mechanism 70 ispropelling a stand alone driving shaft 68 (via sprocket 72) that ismounted on the front axle 64 in a concentric manner via sleeve bearings74. Both ends of stand alone driving shaft 68 are attached to sprockets72 and 76. Sprocket 76 is driving sprocket 78 through ANSI chain 80.Sprocket 78 is attached to second joint 21 driving shaft 82 that isconnected to link 16 in a flange connection and is mounted on link 14axle 84 in a concentric manner via a sleeve bearing 86.

Communication and Electrical Hardware Architecture

Referring to FIGS. 22-25, preferably the electrical hardware in each ofthe segments constituting the robot (two base link 12, second link 14and third link 16) are not connected via wires for data communicationdistribution purposes. The electrical hardware is situated in three ofthe robot's segments—namely, two base link 12 and third link 16. Theelectrical hardware associated with the end-effector or grippermechanism (best seen in FIGS. 26-32) is situated in third link 16 and isnot connected to any of the base link tracks via wires. Each of thesegments contains individual power source (rechargeable batteries) andwireless data transceiver modules for inter-segmental wirelesscommunication.

It will be appreciated by those skilled in the art that the wirelesssystem used herein may be any type of wireless system including forexample an RF (radio frequency) system or an IR (infrared) system. Thespecific example shown herein in FIG. 23 is an RF system and is shown byway of example only.

The right base link track 104 contains a central RF module (FIG. 23( a))for communication with a remote OCU (Operator Control Unit) 105, whileeach of the remaining segments contain RF module for inter-segmentalon-board RF communication. This, along with independent power source ineach segment, eliminates the need for physical wire, wire loops and slipring connections between the rotating segments. This enables each of thesecond link 14 and the third link 16 and the gripper mechanism toprovide continuous rotation about their respective joints without theuse of slip rings and other mechanical means of connection that mayrestrict the range of motion of each link.

The central control system or control module can be located anywhere inthe mobile robot. It does not have to necessarily be located in the baselink. From its location anywhere in the robot, it can communicate withthe other links in the robot and the remote OCU 105 in a wirelessmanner.

By avoiding direct communication between each of the three segments ofthe robot and the OCU, major problems are minimized. Specifically, thereis no need to have a stand-alone vertically sticking out antenna foreach of the robot's segments. Sticking out antennas are not desirabledue to the robot's structural symmetry, which allows the robot toflip-over when necessary and continue to operate with no need ofself-righting. Flat antennas are embedded into the side covers 22 (shownin FIG. 1 and FIG. 31) of the robot for wireless video communication andwireless data communication.

In addition, if each of the base link tracks 104, 106 are receiving datafrom the OCU directly, loss of data due to physical obstructions (walls,trees, buildings, etc.) between transmitter and receiver may result ininconsistent data acquisition by each base link track that may lead tode-synchronization between the track motions. To overcome thislimitation all the data pertaining to all segments of the robot isreceived in one location in the robot and then transmitted anddistributed to the other segments (the segments are separated by fixeddistances from one another with no external physical obstructions), thenthe data received by each of the base link tracks will be virtuallyidentical and any data loss that occurred between the OCU 105 and therobot will be consistent.

Due to the short and fixed distances between the robot's segments/links,the above mentioned problems can be solved by using a low-power on-boardwireless communication between the left 106 and right 104 base linktracks and third link 16.

As shown in FIG. 23, preferably the OCU includes MaxStream 9XCite or9XTend 900 MHz RF Modem. The data transmitted by the stand alone RFmodem OCU 105 is received by a 9XCite or 9XTend OEM RF Module 152(depending on the required range) that is situated in the right baselink track 104 as shown in FIG. 23( a). The 9XCite module 152communicates with the right controller 130 that controls the electronicsin the right base link track while at the same time sends datapertaining to the other segments (left base link track 106 and thirdlink 16) to a MaxStream XBee OEM 2.4 GHz RF Module 142 in a wireconnection. The electronic controls include motors 88, 24 in the rightbase link track, motors 134 in the left base link track and motors 135in the link 16 and associated drivers 136, sensors 138, encoders 140etc. This dada is then transmitted in a wireless manner to two otherXBee OEM 2.4 GHz RF Modules 144 and 146 respectively for the left baselink track 106 and the other for third link 16 (FIGS. 23( b) and (c)).Modules 144 and 146 communicate with left controller 148 and third linkcontroller 150, respectively. Left controller 148 and third linkcontroller 150 control the electronics (motors 134 and associateddrivers 136, sensors 138, encoders 140 etc.) in the left base link trackand gripper mechanism, respectively. The back motor 88 and front motor24 indicated in FIG. 8 are shown in FIG. 23( a). Motor 24 in the frontof the right base link track 104 drives link 14 and motor 24 in thefront of the left base link track 106 drives link 16. The controller 130in base link 104 controls each driver connected to each motor 24 and 88.Similarly, the controller 148 in base link 106 controls each driverconnected to each motor 134 which drive base link 12. The controllerinside link 16 (FIG. 23( c)) controls the drivers that drive the motorsrelated to the gripper mechanism 122.

The major advantages of the XBee OEM RF modules 142, 144 and 146 are:(i) it is available with a PCB chip antenna (FIG. 25), which eliminatesthe need for a vertically sticking out antenna for each link segment ofthe robotic platform; (ii) its operating frequency is 2.4 GHz—namely,different operating frequency than the primary 9Xtend/9Xcite RF module;(iii) fast RF data rate of 250 kbps; and (iv) its small form factor (2.5times 3 cm) saved valuable board space in the compact design of therobot.

The chip antenna is suited for any application, but is especially usefulin embedded applications. Since the radios do not have any issueradiating through plastic cases or housings, the antennas can becompletely enclosed in our application. The XBee RF module with a chipantenna has an indoor wireless link performance of up to 24 m range. Inthe case of the hybrid robot design, the maximum fixed distance betweenthe base link tracks and link 3 is less than 0.5 m.

This concept provides a simple and inexpensive solution when onboardinter-segmental wireless communication is required to avoid any wire andslip-ring mechanical connections between different parts of a givenmechanical system.

Referring to FIG. 24, preferably the controller 130 in each link is aRabbit based core module 152. There are several analog input channels onthe module through which the microcontroller receives signals from thesensors. Each motor in the base link tracks is driven by a motor driver154, which acts as a motor controller to provide position and speedcontrol. Signals from encoders attached to the rear shaft of each motorare sent to the drivers as feedback. A socket 156 to the microcontrolleris reserved for other signals, which may be added in the future. Asshown in FIGS. 24 and 31, there are two cameras 112, 114 located in thefront and back of the left base link track, which provide visualinformation to the OCU operator on the robot's surroundings. A videotransmitter 158 is used to transmit the video signals to the OCU 105. Aswitch controlled by the microcontroller 152. Note, this microcontroller152 is stand alone, and can be connected to any of the controllers thatexist in the left or right track decides the image of which camera isbeing transmitted. In addition audio signals may also be transmitted tothe OCU 105.

Power is generally one of the constraining factors for small robotdesign. In order to generate the required torques for each linkincluding the gripper mechanism, preferably rechargeable Lithium-Ionbattery units in a special construction with the inclusion of ProtectionCircuit Modules (PCMs) are used in order to safely generate high currentdischarge based on the motors demands. With the combination of thispower source along with a proper selection of brushless DC motors andharmonic gear-head drives, high torques can be generated. Each of theleft 106 and right 104 base link tracks and the gripper mechanismsituated in the space provided in third link 16 has a standalone powersource.

It will be appreciated by those skilled in the art that the embodimentsshown herein are by way of example and a number of variations ormodification could be made to the embodiment whilst staying within theinvention. For example, each miter gear 40 and 98 could be replaced witha bevel gear to allow any ratio greater than 1:1 to generate any desiredtorque to drive link 14 or link 16. For the same purpose, variousdiameter combinations for sprocket gears 46 and 100 can be selected toprovide any desired torque value to drive pulley 26 and links 14 or 16.The front driving mechanism 70 and the back driving mechanism 90 can bereconfigured with different gear constructions and ratios to generatetorque for driving the pulley 26 and links 14 or 16. For instance, theback driving mechanism can be changed such that the miter gear 40 and 98and the sprocket gears 46 and 100 can be replaced altogether with onebevel gear set such that the driving bevel gear is attached to the motor88 output shaft and the driven bevel gear is attached directly on thepulley 26. The motors 24 and 88 also can be reoriented differentlyinside the base links 12 to allow different gear constructions ofdriving mechanisms 70 and 90. Additional gear head types such asharmonic drives and planetary gears can be placed between drivingmechanisms 70 and 90 and motors 24 and 88 respectively to generate anydesired torque to drive link 14 or link 16. As well, the thrust bearing56 is optional in the design. Further it will be appreciated that therobot may include more than three links. Rather the robot may includemultiple links forming a snake-like robot.

Referring to FIG. 26, the hybrid mobile robot of the present inventionmay have wheels 160, rather than tracks 20. Wheels 160 are attached tobase links 12. Base links 12, second link 14 and third link 16 are asdescribed above. An end effector 122 is pivotally connected to thirdlink 16. In the stowed or closed configuration shown in FIG. 26( d) endeffector is nested in link 16 such that no part of end effector 122 isabove or below link 16. Similarly link 16 is nested in link 14 and link14 is nested between base links 12.

Referring to FIGS. 27 to 29, the positioning of the base links 12, thesecond link 14 and third link 16 may vary depending on the particularconfiguration. For example right and left base links 12 of the hybridmobile robot of the present invention can be aligned proximate to eachother, and joined at the front and the back, rather than spaced apartfrom each other. It will be appreciated by those skilled in the art thatrather the two base links shown herein could be combined as a singlebase link. In these alternative embodiments, the second link 14 may foldby the side of the base links 12 and the third link 16 nests inside thesecond link 14 as shown in FIG. 27. Alternatively the third link 16 mayfold by the side of the second link 14 as shown in FIG. 28. In a furtheralternative the second link 14 may be attached to one of the right andleft base links 12, while the third link 16 is attached to the other ofbase links as shown in FIG. 29.

The embodiment shown in FIG. 29 also provides an additional oralternative location for an end effector. For example, since the thirdlink 16 is attached to one of the base links 12, rather than to orinside the second link 14, a space is available for the second link 14to have an additional end effector at its end (not shown). Furthermore,an additional link 16 with an end effector 122 can be attached to one ofthe base links. In one possible embodiment, one link 16 with endeffector 122 can be attached to one end of one of the base links 12,while an additional link 16 with end effector 122 is nested inside link14 that is attached to the other end of the other base link, which willincrease the available locations for end effectors (not shown).

Referring to FIG. 30, the hybrid mobile robot of the present inventionmay be configured wherein the pair or first and second base links 12 areattached at the front and back and the second link is shorter than thebase links and consequently the third link is shorter and in theprevious embodiments. Passive wheels 120 can be added on third joint 25(shown in FIG. 31) between the gripper mechanism that occupies the spacein link 16 and link 16. The passive wheels are used to enhance themobility capability of the platform when link 16 is used to support theentire platform for various mobility requirements. Referring to FIG. 31,a fully loaded robot is shown at 131. The fully loaded robot 130includes an end effector 122 and different type of accessories that areusually imbedded in a mobile robot. Robot 130 has embedded flat datawireless antenna 108, embedded flat video wireless antenna 110, frontand back CCD cameras 112, 114, front and back LED lights 116, 118. Oneantenna is used to transmit and receive traction and manipulationsignals to the central control system and a second antenna is used totransmit and receive audio and video signals.

In another aspect of the present invention, the different links can beattached and detached to arrive at any of the various configurationsaccording to the desired application.

It will be appreciate by those skilled in the art that in all of theembodiments shown herein the robot may flip over or be inverted. Inorder to facilitate this, the robot has a stowed position. The baselinks 12 define an upper plane and a lower plane, similarly the secondlink 14 defines a second link upper plane and lower plane; the thirdlink 16 defines a third link upper plane and lower plane; and the endeffector 122 defines an end effector upper and lower plane. In thestowed position the second link upper and lower plane, the third linkupper and lower plane and the end effector upper and lower plane are allwithin the upper and lower plane of the base links. The embodimentsshown in FIGS. 1 to 9, 26, 30 and 31 have a stowed position wherein thesecond link 14 is nested between spaced apart first and second baselinks 12, the third link 16 is nested in the second link 14.

It will be appreciated by those skilled in the art that the embodimentsof the present invention provide solutions to a series of major issuesrelated to the design and operation of mobile robots operating on roughterrain. Specifically the embodiments of the invention shown herein havemajor two advantages. The embodiments of the invention provide a novelapproach for a mobile robot where the mobile platform and themanipulator arm are one entity rather than two separate and attachedmodules. In other words, the mobile platform is used as a manipulatorarm and vice versa. This way, the same joints (motors) that provide themanipulator's dof's, also provide the mobile platform's dof's. As wellthe embodiments of the invention herein enhance the robot's mobility by“allowing” it to flip-over and continue to operate instead of trying toprevent the robot from flipping-over or attempting to return it(self-righteousness). When a flip-over takes place, the user only needsto command the robot to continue to its destination from the currentposition.

Each item of the idea has its own advantages, and each one is an idea byitself. Furthermore, the two parts of the idea complement each other. Inthe embodiments of the present invention described herein, the mobileplatform is part of the manipulator arm, and the arm is also part of theplatform. As fewer components are required (approximately 50% reductionin the number of motors), the embodiments herein result in a muchsimpler and robust design, significant weight reduction and lowerproduction cost. Another feature of the embodiments herein is that thearm and platform are designed as one entity, and the arm is part of theplatform. This eliminates the exposure of the arm to the surroundingswhile the robot is heading to a target perhaps in close and narrowsurroundings (e.g. an underground tunnel). As soon as the target isreached, the arm is deployed in order to execute desired tasks. Sincethe arm is part of the platform, it is not exposed to the surroundings,and the mobility is enhanced. In the embodiments herein the platform issymmetric and is therefore able to continue to the target from anyorientation with no need of self-righting when it falls or flips over.This enhances considerably the ability of the robot to adapt to theterrain according to the needed degree of maneuverability and traction.Further when the robot encounters an obstacle or a steep inclination inthe terrain it is sometimes inevitable and hence preferable to let therobot fall and roll, and continue its mission without self-righting inorder to reach the target sooner.

A major advantage of the new design paradigm is that it is scalable. Itcan be applied to small backpack-able as well as large track-transportedEOD (Explosive Ordnance Disposal) mobile robots.

Generally speaking, the systems described herein are directed to hybridmobile robots. As required, embodiments of the present invention aredisclosed herein. However, the disclosed embodiments are merelyexemplary, and it should be understood that the invention may beembodied in many various and alternative forms. The figures are not toscale and some features may be exaggerated or minimized to show detailsof particular elements while related elements may have been eliminatedto prevent obscuring novel aspects. Therefore, specific structural andfunctional details disclosed herein are not to be interpreted aslimiting but merely as a basis for the claims and as a representativebasis for teaching one skilled in the art to variously employ thepresent invention. For purposes of teaching and not limitation, theillustrated embodiments are directed to hybrid mobile robots.

As used herein, the term “about”, when used in conjunction with rangesof dimensions, temperatures or other physical properties orcharacteristics is meant to cover slight variations that may exist inthe upper and lower limits of the ranges of dimensions so as to notexclude embodiments where on average most of the dimensions aresatisfied but where statistically dimensions may exist outside thisregion.

As used herein, the terms “comprises” and “comprising” are to construedas being inclusive and opened rather than exclusive. Specifically, whenused in this specification including the claims, the terms “comprises”and “comprising” and variations thereof mean that the specifiedfeatures, steps or components are included. The terms are not to beinterpreted to exclude the presence of other features, steps orcomponents.

1. A mobile robot comprising: a chassis; and a pair of track drive pulley systems, one on each side of the chassis, each track drive pulley system having a front and back pulley, a track, and a plurality of top and bottom spaced apart planetary supporting pulleys, each pulley having a tension and suspension mechanism.
 2. A mobile robot as claimed in claim 1 wherein the plurality of planetary supporting pulleys are divided into a top facing set and a bottom facing set and wherein the top facing set acts as a tension mechanism for the tracks and the bottom facing set acts as a suspension mechanism.
 3. A mobile robot as claimed in claim 2 wherein the top facing set and the bottom facing set are interchangeable between tension and suspension.
 4. A mobile robot as claimed in claim 1 wherein each tension and suspension mechanism includes a compression spring seated in a spring housing and wherein the tension and suspension mechanism restricts an upward and a downward displacement to a predetermined value. 